SimpleDbResultConverter.java

package org.springframework.data.simpledb.query;

import org.springframework.data.simpledb.reflection.ReflectionUtils;

import java.util.*;

/**
 * This class convert the list of entities retrieved from db to the returned type needed by the query method
 */
public final class SimpleDbResultConverter {

	private SimpleDbResultConverter() {
		/* utility class */
	}

	public static List<Object> filterNamedAttributesAsList(List<?> domainObjects, String attributeName) {
		List<Object> ret = new ArrayList<Object>();
		for(Object object : domainObjects) {
			ret.add(ReflectionUtils.callGetter(object, attributeName));
		}
		return ret;
	}

	public static Set<Object> filterNamedAttributesAsSet(List<?> domainObjects, String attributeName) {
		Set<Object> ret = new LinkedHashSet<Object>();
		for(Object object : domainObjects) {
			ret.add(ReflectionUtils.callGetter(object, attributeName));
		}
		return ret;
	}

	public static List<List<Object>> toListOfListOfObject(List<?> entityList, List<String> requestedQueryFieldNames) {
		if(entityList.size() > 0) {
			List<List<Object>> rows = new ArrayList<List<Object>>();
			for(Object entity : entityList) {
				List<Object> cols = new ArrayList<Object>();
				for(String fieldName : requestedQueryFieldNames) {
					Object value = ReflectionUtils.callGetter(entity, fieldName);
					cols.add(value);
				}
				rows.add(cols);
			}
			return rows;
		} else {
			return Collections.emptyList();
		}
	}

}